Custom microcontroller using only a Dremel

Check out this 6-pin MSP430 microcontroller. What’s that you say? TI doesn’t make a 6-pin MSP430? True, Texas Instruments doesn’t make one, so [Greg] grabbed his Demel and a cutoff wheel, and chopped up a larger uC to arrive at this package.

It may sound a bit crazy at first, but when you think about it there’s nothing really all that special about this. The plastic package on DIP components these days is mostly empty. The silicon die which does the computing is quite small in comparison, and usually mounted in the very center of the part. [Greg] simply cut off eight of the unneeded pins (four from each end).

Well, it might be a stretch to call them unneeded since he cut the ground and voltage pins. He gets around this issue by taking advantage of the same properties of the I/O pins used in this barebones RFID tag. You can inject power through the I/O and we’d bet you could easily use this chopped-up MSP430G2211 as an RFID tag if you wanted to.

TI makes MSP430s in DIP format, just not in 6-pin DIP, which was sort of the point of this amusing hack. Most of the chips are 14-pin or 20-pin DIP, and also available in several different surface-mount packages. He’s doing something like sawing off an ATmega chip to make an ATtiny.

If you want surface-mount, you’re welcome to it, but this lets him put it on a solderless breadboard.

A dremel tool with a cutoff wheel probably generates a fair amount of ESD as it eats its way through the epoxy. In addition, vibration and stress is transferred to the die and its bond wires as the cutting tool bites into the lead frame. If the die and bond wires are not directly affected, at the very least, the cutting operation may result in tiny cracks or separation between the lead frame and epoxy, leading to the ingress of air and moisture.

The bottom line is that just because the modified part “seems” to work, doesn’t mean that significant latent damage hasn’t occurred.

I applaud this as a clever trick, but it strikes me as the solution to a problem that doesn’t really exist.

If you’re prototyping something, who cares what size the package is? Usually, you just want some hardware to test your code on. On the other hand, if you’re deploying the gizmo into the real world, the presumption is that the finished device needs to work reliably. Why would you use a compromised part? If it really needs to be tiny, use a surface mount part.

I have done this before but not to make a smaller chip. I once broke off a pin on a chip I really needed and that pin that broke was the VCC . I used a dremel tool and cutoff wheel to cut away the casing until there was enough of the pin to solder to.

While there may be some ESD risks (probably little more than what may happen through careless handling), I think is an interesting idea of adjusting the package to something that may be more useful. Think dead-bug but on steroids!
There probably are other standard packages that are small but I can see one could re-route the VCC/GND pins onto the top & bottom of a DIL package to keep it all compact.

This is actually a clever idea. Often chips like PICs, AVRs and, apparently MSP430s think that the devices in smaller packages don’t need as much RAM, Flash, timers, etc… This is a decent way to get a smaller package with, perhaps, “bigger” features.

I think it’s interesting how often comments like “you’ll break it with ESD!” occur with the commenter probably has no idea what they’re talking about. Have you tried it? do you know? what was your experimental method? An experiment is worth a million half-baked theories.

Experimenting in ESD land is hard. ESD damage can linger for years before it causes problems. If you want to know if it’s ESD damaged, you’ll have to do your abuse, then de-cap the chip and use an electron microscope to check it for damage. It’s the only way to be sure, and I don’t have that kind of equipment in my basement.

I know something about the subject. I have to undergo annual mandatory ESD training/testing/certification at the electronics facility I work at. I have observed the effects of latent damage first hand, and have seen photo-micrographs of visible damage done to “good” parts from static pulses that were too small to be felt by the human hand.

The company I work for (like any in the electronics industry) has spent untold millions of dollars deploying protective containers, shielding, grounding, climate controls, monitoring and ionization equipment, as well as implementing specific training and handling processes. This is done to protect electronic parts including those that are far less less static sensitive than a cmos micro.

So, in answer to your questions…
a)We try NOT to do it.
b)No “experiments” necessary, because real-world data trumps hypotheticals.
c)Pictures of half-blown traces on a die carry more weight than your “half-baked” comments.

I submit that the only person who doesn’t seem to know what he’s talking about here is *you.*

You are not who he was talking to. He was talking to the people who just parrot the warnings that others do, in a tone that implies they know what they are talking about.

You, clearly, are not just parroting. You, clearly, know what you’re talking about – and every one of those instances where you’ve seen the damage – that’s an “experiment” – because it actually happened and you actually witnessed it. You didn’t just assume it would happen.

It’s not nearly that simple. You have to look at it from a risk perspective.

You work for a manufacturer who has to sell equipment with a specified (high) factor of reliability. Warranty work is very expensive in terms of direct costs and customer satisfaction, and depending on what you’re assembling, possible indirect costs, too. An ABS controller failure might cause a car crash complete with eight figure lawsuits, for example. So for your company, even one failure in 10,000 is far too high. Therefore your company spends tons of money to be sure that a preventable problem that has a proven solution is actually prevented.

@Greg is a guy on his kitchen table. One failure in 5 may be perfectly acceptable odds to him. Or latent damage may be of no concern, as long as his experiment works once or twice. Maybe he’s building a costume that has to last for the first 30 minutes of a party, until everyone’s too drunk to notice it stopped working.

I think it’s great that you provided such a technically detailed explanation, because that certainly helps all the HaD readers understand the risks of ESD. But depending on his usage, @Greg will probably be able to achieve his goals without heeding your warnings or even to bother understanding ESD. It’s not that he won’t damage his chips, it’s just that it may not be worth the worry to him.

Yeah, yeah, ESD is certainly possible. So is cutting off a bit too much functional metal if your hand slips with the Dremel, or after you’ve installed it water could get into the package. If you were making production systems that needed to be safety-critical or would disappoint your kid if they stopped working halfway into trick-or-treating, then you probably wouldn’t do this.

But he’s not, he’s just making a cool hack because it’s fun, and prototyping it on a breadboard. He’s sawing an integrated circuit in half, and Magic! It still works!

Of course it is a great example of thinking out of the box and for the sake of hacking parts…

In the end I´d rather be afraid of moisture reaching the die or the now exposed sides and searching for some real weird problems in the end. It may be a bad idea to place such a part in a project and trying to debug.

Potential ESD damage aside, in many chips, you shouldn’t just leave pins floating when not in use. They should be grounded. I would hope that the OP looked at the pinout to see what was necessary before doing this.

In any case, as others have mentioned, it’d probably be easier to do some SMT soldering :)

I’ve done this with pic microcontrollers to embed them in prototype smartcards. you can also mill the bottom until you reach the metallic base. The only problem is the top part, if you go too deep you’ll find the silicon so be conservative there.

Besides the “Look guys what I can do” this looks quite useless. If you want to prototype, you can use the larger device on the proto-board. If you want to do something more durable on a PCB, either use the unchopped device or SMD/SMT.
The only case where this would be useful is when trying to repair (or add extra functionality to) an old device and you don’t have the physical space to fit the large device so you’re forced to cut it.
Anyways, it was an interesting read. I’ve always wondered if this could be done, now I know. But I won’t use it :P